diff --git a/Makefile b/Makefile
index ff450cb..19a9196 100644
--- a/Makefile
+++ b/Makefile
@@ -5,3 +5,6 @@ morris.js: morris.coffee
 
 morris.min.js: morris.js
 	uglifyjs morris.js > morris.min.js
+
+clean:
+	rm -f morris.js morris.min.js